WITHIN-LINE HETEROGENEITY FOR GENE sbm IN THE U.S. PI SUM COLLECTION

PNL Volume 12 1980

RESEARCH REPORTS 27

Hampton, R. 0. US Dept. Agric. Oregon State Univ., Corvallis, OR U.S.A.

During a recent search (1) for sources of immunity to pea seedborne

mosaic virus [gene sbm (2)] among 668 untested U.S. Plant Introduction

accessions of Pisum, 16 lines homogeneous for immunity were identified. The

16 lines were released to U.S. plant breeders by special memorandum in

October, 1976. Having been selected specifically for PSbMV-immunity, these

lines represented the usual gamut of non-horticultural plant characteristics.

Numerous other lines, however, consisted of obvious mixtures of seed and

plant type, but contained a majority of immune plants, and still others con-

tained a minority of immune plants.

These results prompted the question: is the sbm allele relatively common

in the USDA collection of Pisum? If so, might a diverse source of sbm provide

breeders with a better choice of horticultural characteristics for breeding

purposes than is available in the released lines?

I therefore examined data from the above 668 lines to identify those

that were previously excluded on the basis of either seed or plant type mix-

tures, or heterogeneity for gene sbm (not pure for sbm/sbm plants). Resis-

tance was found in 160 lines in addition to the 16 previously released to

28 RESEARCH REPORTS

PNL Volume 12 1980

plant breeders. Some of these (Table 1) offered plant characteristics

generally superior to those of lines already released and consequently might

serve as good sources of resistance.

It must be stressed, however, that if accessions such as PI 314795,

347795, and 347528, which were found to contain mixtures of susceptible

and immune types, were selected as a source of sbm, then the persons attempting

to utilize this source would need to be equipped to detect and eliminate

susceptible plants from the stock prior to use. Less than stringent measures,

in this case, would permit introduction of PSbMV into a program, predisposing

susceptible materials to infection.

1. Hampton, R. 0. and S. W. Braverman. 1979. Plant Dis. Reptr. 63:95-99.

2. Hagedorn, 1). J. and E. T. Gritton. 1973. Phytopathology 63:1130-1133.